Control Device Having a Secondary Radio for Waking up a Primary Radio

ABSTRACT

A control device may comprise a primary radio circuit for receiving radio-frequency signals via an antenna, and a secondary radio circuit for waking up the primary radio circuit when a radio-frequency signal is presently being transmitted by an external device. The control device may include a control circuit that may be coupled to the primary radio circuit, and may control the primary radio circuit into a sleep mode. The secondary radio circuit may generate a first control signal indicating that the radio-frequency signal is presently being transmitted by the external device. The control circuit may wake up the primary radio circuit from the sleep mode in response to the secondary radio circuit generating the first control signal indicating that the radio-frequency signal is presently being transmitted by the external device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/838,362, filed Apr. 25, 2020, the entire disclosureof which is hereby incorporated by reference.

BACKGROUND

A user environment, such as a residence or an office building forexample, may be configured using various types of load control systems.A lighting control system may be used to control the lighting loads inthe user environment. A motorized window treatment control system may beused to control the natural light provided to the user environment. Aheating, ventilation, and cooling (HVAC) system may be used to controlthe temperature in the user environment. Each load control system mayinclude various control devices, including control-source devices andcontrol-target devices. The control-target devices may receive messages(e.g., digital messages), which may include load control instructions,for controlling an electrical load from one or more of thecontrol-source devices. The control-target devices may be capable ofdirectly controlling an electrical load. The control-source devices maybe capable of indirectly controlling the electrical load via thecontrol-target device. Examples of control-target devices may includelighting control devices (e.g., a dimmer switch, an electronic switch, aballast, or a light-emitting diode (LED) driver), a motorized windowtreatment, a temperature control device (e.g., a thermostat), an plug-inload control device, and/or the like. Examples of control-source devicesmay include remote control devices, occupancy sensors, daylight sensors,temperature sensors, and/or the like.

SUMMARY

As described herein, a control device (e.g., a battery-powered controldevice, such as a battery-powered motorized window treatment) mayoperate in a sleep mode to conserve power and may wake up periodicallyto determine if the control device is receiving radio-frequency signalsfrom an external device (e.g., such as a remote control device and/or asystem controller). The control device may comprise a primary radiocircuit for receiving the radio-frequency signals via an antenna, and asecondary radio circuit for waking up the primary radio circuit when aradio-frequency signal is presently being transmitted by the externaldevice. The control device may include a control circuit that may becoupled to the primary radio circuit, and may control the primary radiocircuit into a sleep mode. The secondary radio circuit may generate afirst control signal indicating that the radio-frequency signal ispresently being transmitted by the external device. The control circuitmay wake up the primary radio circuit from the sleep mode in response tothe secondary radio circuit generating the first control signalindicating that the radio-frequency signal is presently beingtransmitted by the external device. For example, the secondary radiocircuit may consume less power than the primary radio circuit, such thatthe control device consumes less power when the secondary radio circuitis used to wake up the primary radio circuit than when the controldevice comprises only the primary radio circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an example load control system.

FIG. 2 is a block diagram of an example control device having asecondary radio circuit for waking up a primary radio circuit.

FIG. 3 illustrates example waveforms of the control device of FIG. 2.

FIG. 4 is a flowchart of an example control procedure that may beexecuted by a secondary microprocessor of a control device toperiodically wake up a secondary radio circuit to determine if aradio-frequency signal is presently being transmitted.

FIG. 5 is a flowchart of an example control procedure that may beexecuted by a primary microprocessor of a control device to wake up aprimary radio circuit and receive a radio-frequency signal.

DETAILED DESCRIPTION

FIG. 1 is a diagram of an example load control system 100 forcontrolling an amount of power delivered from a power source (notshown), such as an alternating-current (AC) power source or adirect-current (DC) power source, to one or more electrical loads. Theload control system 100 may be installed in a room 102 of a building.The load control system 100 may comprise a plurality of control devicesconfigured to communicate with each other by transmitting and receivingmessages (e.g., digital messages) via wireless signals, e.g.,radio-frequency (RF) signals 108. Alternatively or additionally, theload control system 100 may comprise a wired digital communication linkcoupled to one or more of the control devices to provide forcommunication between the control devices. The control devices of theload control system 100 may comprise a number of control-source devices(e.g., input devices operable to transmit digital messages in responseto user inputs, occupancy/vacancy conditions, changes in measured lightintensity, etc.) and a number of control-target devices (e.g., loadcontrol devices operable to receive digital messages and controlrespective electrical loads in response to the received digitalmessages). A single control device of the load control system 100 mayoperate as both a control-source and a control-target device.

The control-source devices may be configured to transmit digitalmessages directly to the control-target devices. In addition, the loadcontrol system 100 may comprise a system controller 110 (e.g., a centralprocessor or load controller) configured to communicate digital messagesto and from the control devices (e.g., the control-source devices and/orthe control-target devices). For example, the system controller 110 maybe configured to receive digital messages from the control-sourcedevices and transmit digital messages to the control-target devices inresponse to the digital messages received from the control-sourcedevices.

The load control system 100 may comprise one or more load controldevices, such as a dimmer switch 120 (e.g., a control-target device) forcontrolling a lighting load 122. The dimmer switch 120 may be configuredto control an amount of power delivered from the AC power source to thelighting load to adjust an intensity level and/or a color (e.g., a colortemperature) of the lighting load. The dimmer switch 120 may be adaptedto be wall-mounted in a standard electrical wallbox. The dimmer switch120 may also comprise a tabletop or plug-in load control device. Thedimmer switch 120 may comprise a toggle actuator (e.g., a button) and anintensity adjustment actuator (e.g., a rocker switch). Actuations (e.g.,successive actuations) of the toggle actuator may toggle (e.g., turn offand on) the lighting load 122. Actuations of an upper portion or a lowerportion of the intensity adjustment actuator may respectively increaseor decrease the amount of power delivered to the lighting load 122 andthus increase or decrease the intensity of the receptive lighting loadfrom a minimum intensity (e.g., approximately 1%) to a maximum intensity(e.g., approximately 100%). The dimmer switch 120 may comprise aplurality of visual indicators, e.g., light-emitting diodes (LEDs),which are arranged in a linear array and are illuminated to providefeedback of the intensity of the lighting load 122. Examples ofwall-mounted dimmer switches are described in greater detail in U.S.Pat. No. 9,679,696, issue Jun. 13, 2017, entitled WIRELESS LOAD CONTROLDEVICE, the entire disclosure of which is hereby incorporated byreference.

The dimmer switch 120 may comprise an internal power supply for poweringthe electrical circuitry of the dimmer switch. The dimmer switch 120 maybe a “two-wire” dimmer switch (e.g., may not be connected to a neutralside of the AC power source) and the power supply may be configured toconduct a charging current through the lighting load 122 for generatinga supply voltage. In addition, the dimmer switch 120 may comprise anearth ground connection, and may be configured to conduct the chargingcurrent of the power supply through the earth ground connection.

The dimmer switch 120 may be configured to wirelessly receive digitalmessages via the RF signals 108 (e.g., from the system controller 110)and to control the lighting load 122 in response to the received digitalmessages. Examples of dimmer switches and other control devicesconfigured to transmit and receive digital messages are described ingreater detail in commonly-assigned U.S. Pat. No. 10,041,292, issuedAug. 7, 2018, entitled LOW-POWER RADIO-FREQUENCY RECEIVER, and U.S. Pat.No. 10,271,407, issued Apr. 23, 2019, entitled LOAD CONTROL DEVICEHAVING INTERNET CONNECTIVITY, the entire disclosures of which are herebyincorporated by reference.

The load control system 100 may comprise one or more remotely-locatedload control devices, such as a light-emitting diode (LED) driver 130(e.g., a control-target device) for driving an LED light source 132(e.g., an LED light engine). The LED driver 130 may be located remotely,for example, in or adjacent to the lighting fixture of the LED lightsource 132. The LED driver 130 may be configured to receive digitalmessages via the RF signals 108 (e.g., from the system controller 110)and to control the LED light source 132 in response to the receiveddigital messages. The LED driver 130 may be configured to adjust thecolor temperature of the LED light source 132 in response to thereceived digital messages. The load control system 100 may furthercomprise other types of remotely-located load control devices, such as,for example, electronic dimming ballasts for driving fluorescent lamps.

The load control system 100 may comprise a plug-in load control device140 (e.g., a control-target device) for controlling a plug-in electricalload, e.g., a plug-in lighting load (e.g., such as a floor lamp 142 or atable lamp) and/or an appliance (e.g., such as a television or acomputer monitor). For example, the floor lamp 142 may be plugged intothe plug-in load control device 140. The plug-in load control device 140may be plugged into a standard electrical outlet 144 and thus may becoupled in series between the AC power source and the plug-in lightingload. The plug-in load control device 140 may be configured to receivedigital messages via the RF signals 108 (e.g., from the systemcontroller 110) and to turn on and off or adjust the intensity of thefloor lamp 142 in response to the received digital messages.

Alternatively or additionally, the load control system 100 may comprisecontrollable receptacles (e.g., control-target devices) for controllingplug-in electrical loads plugged into the receptacles. The load controlsystem 100 may comprise one or more load control devices or appliancesthat are able to directly receive the wireless signals 108 from thesystem controller 110, such as a speaker 146 (e.g., part of anaudio/visual or intercom system), which is able to generate audiblesounds, such as alarms, music, intercom functionality, etc.

The load control system 100 may comprise one or more daylight controldevices, e.g., motorized window treatments 150 (e.g., control-targetdevices), such as motorized cellular shades or roller shades, forcontrolling the amount of daylight entering the room 102. Each motorizedwindow treatments 150 may comprise a window treatment fabric 152 hangingfrom a headrail 154 in front of a respective window. Each motorizedwindow treatment 150 may further comprise a motor drive unit 155 locatedinside of the headrail 154 for raising and lowering the window treatmentfabric 152 for controlling the amount of daylight entering the room 102.The motor drive units 155 of the motorized window treatments 150 may beconfigured to receive digital messages via the RF signals 108 (e.g.,from the system controller 110) and adjust the position of therespective window treatment fabric 152 in response to the receiveddigital messages. The motor drive unit 155 of each motorized windowtreatment 150 may be battery-powered or may be coupled to an externalalternating-current (AC) or direct-current (DC) power source. Inaddition, the motorized window treatments 150 may comprise internalstorage elements, such as supercapacitors and/or rechargeable batteries,and may be configured to charge (e.g., trickle charge) the internalstorage elements from a DC power source via a power bus (e.g., bydrawing a small amount of current via the power bus). The load controlsystem 100 may comprise other types of daylight control devices, suchas, for example, a cellular shade, a drapery, a Roman shade, a Venetianblind, a Persian blind, a pleated blind, a tensioned roller shadesystems, an electrochromic or smart window, and/or other suitabledaylight control device. Examples of battery-powered motorized windowtreatments are described in greater detail in U.S. Pat. No. 10,494,864,issued Dec. 3, 2019, entitled MOTORIZED WINDOW TREATMENT, the entiredisclosure of which is hereby incorporated by reference.

The load control system 100 may comprise one or more temperature controldevices, e.g., a thermostat 160 (e.g., a control-target device) forcontrolling a room temperature in the room 102. The thermostat 160 maybe coupled to a heating, ventilation, and air conditioning (HVAC) system162 via a control link (e.g., an analog control link or a wired digitalcommunication link). The thermostat 160 may be configured to wirelesslycommunicate digital messages with a controller of the HVAC system 162.The thermostat 160 may comprise a temperature sensor for measuring theroom temperature of the room 102 and may control the HVAC system 162 toadjust the temperature in the room to a setpoint temperature. The loadcontrol system 100 may comprise one or more wireless temperature sensors(not shown) located in the room 102 for measuring the room temperatures.For example, the thermostat 160 and the wireless temperature sensors maybe battery-powered. The HVAC system 162 may be configured to turn acompressor on and off for cooling the room 102 and to turn a heatingsource on and off for heating the rooms in response to the controlsignals received from the thermostat 160. The HVAC system 162 may beconfigured to turn a fan of the HVAC system on and off in response tothe control signals received from the thermostat 160. The thermostat 160and/or the HVAC system 162 may be configured to control one or morecontrollable dampers to control the air flow in the room 102.

The load control system 100 may comprise one or more other types of loadcontrol devices (e.g., control-target devices), such as, for example, ascrew-in luminaire including a dimmer circuit and an incandescent orhalogen lamp; a screw-in luminaire including a ballast and a compactfluorescent lamp; a screw-in luminaire including an LED driver and anLED light source; an electronic switch, controllable circuit breaker, orother switching device for turning an appliance on and off; a plug-inload control device, controllable electrical receptacle, or controllablepower strip for controlling one or more plug-in loads; a motor controlunit for controlling a motor load, such as a ceiling fan or an exhaustfan; a drive unit for controlling a motorized window treatment or aprojection screen; motorized interior or exterior shutters; a thermostatfor a heating and/or cooling system; a temperature control device forcontrolling a setpoint temperature of an HVAC system; an airconditioner; a compressor; an electric baseboard heater controller; acontrollable damper; a variable air volume controller; a fresh airintake controller; a ventilation controller; a hydraulic valves for useradiators and radiant heating system; a humidity control unit; ahumidifier; a dehumidifier; a water heater; a boiler controller; a poolpump; a refrigerator; a freezer; a television or computer monitor; avideo camera; an audio system or amplifier; an elevator; a power supply;a generator; an electric charger, such as an electric vehicle charger;and an alternative energy controller.

The load control system 100 may comprise one or more input devices(e.g., control-source devices), such as a remote control device 170, anoccupancy sensor 172, and/or a daylight sensor 174. The input devicesmay be fixed or movable input devices. The remote control device 170,the occupancy sensor 172, and/or the daylight sensor 174 may be wirelesscontrol devices (e.g., RF transmitters) configured to transmit digitalmessages via the RF signals 108 to the system controller 110 (e.g.,directly to the system controller). The system controller 110 may beconfigured to transmit one or more digital messages to the load controldevices (e.g., the dimmer switch 120, the LED driver 130, the plug-inload control device 140, the motorized window treatments 150, and/or thethermostat 160) in response to the digital messages received from theremote control device 170, the occupancy sensor 172, and/or the daylightsensor 174. The remote control device 170, the occupancy sensor 172,and/or the daylight sensor 174 may be configured to transmit digitalmessages directly to the dimmer switch 120, the LED driver 130, theplug-in load control device 140, the motorized window treatments 150,and the temperature control device 160.

The remote control device 170 may be configured to transmit digitalmessages to the system controller 110 via the RF signals 108 in responseto an actuation of one or more buttons of the remote control device. Forexample, the remote control device 170 may be battery-powered.

The occupancy sensor 172 may be configured to detect occupancy andvacancy conditions in the room 102 (e.g., the room in which theoccupancy sensors are mounted). For example, the occupancy sensor 172may be battery-powered. The occupancy sensor 172 may transmit digitalmessages to the system controller 110 via the RF signals 108 in responseto detecting the occupancy or vacancy conditions. The system controller110 may be configured to turn the lighting loads (e.g., lighting load122 and/or the LED light source 132) on and off in response to receivingan occupied command and a vacant command, respectively. The occupancysensor 172 may operate as a vacancy sensor, such that the lighting loadsare only turned off in response to detecting a vacancy condition (e.g.,and not turned on in response to detecting an occupancy condition).Examples of RF load control systems having occupancy and vacancy sensorsare described in greater detail in commonly-assigned U.S. Pat. No.8,009,042, issued Aug. 30, 2011, entitled RADIO-FREQUENCY LIGHTINGCONTROL SYSTEM WITH OCCUPANCY SENSING, the entire disclosure of which ishereby incorporated by reference.

The daylight sensor 174 may be configured to measure a total lightintensity in the room 102 (e.g., the room in which the daylight sensoris installed). For example, the daylight sensor 174 may bebattery-powered. The daylight sensor 174 may transmit digital messages(e.g., including the measured light intensity) to the system controller110 via the RF signals 108 for controlling the intensities of thelighting load 122 and/or the LED light source 132 in response to themeasured light intensity. Examples of RF load control systems havingdaylight sensors are described in greater detail in commonly-assignedU.S. Pat. No. 8,451,116, issued May 28, 2013, entitled WIRELESSBATTERY-POWERED DAYLIGHT SENSOR, the entire disclosure of which ishereby incorporated by reference.

The load control system 100 may comprise other types of input devices,such as, for example, temperature sensors, humidity sensors,radiometers, cloudy-day sensors, shadow sensors, pressure sensors, smokedetectors, carbon monoxide detectors, air-quality sensors, motionsensors, security sensors, proximity sensors, fixture sensors, partitionsensors, keypads, multi-zone control units, slider control units,kinetic or solar-powered remote controls, key fobs, cell phones, smartphones, tablets, personal digital assistants, personal computers,laptops, timeclocks, audio-visual controls, safety devices, powermonitoring devices (e.g., such as power meters, energy meters, utilitysubmeters, utility rate meters, etc.), central control transmitters,residential, commercial, or industrial controllers, and/or anycombination thereof.

The system controller 110 may be configured to be coupled to a network,such as a wireless or wired local area network (LAN), e.g., for accessto the Internet. The system controller 110 may be wirelessly connectedto the network, e.g., using a WI-FI network. The system controller 110may be coupled to the network via a network communication bus (e.g., anEthernet communication link).

The system controller 110 may be configured to communicate via thenetwork with one or more network devices, e.g., a mobile device 180,such as, a personal computing device and/or a wearable wireless device.The mobile device 180 may be located on an occupant 182, for example,may be attached to the occupant's body or clothing or may be held by theoccupant. The mobile device 180 may be characterized by a uniqueidentifier (e.g., a serial number or address stored in memory) thatuniquely identifies the mobile device 180 and thus the occupant 182.Examples of personal computing devices may include a smart phone, alaptop, and/or a tablet device. Examples of wearable wireless devicesmay include an activity tracking device, a smart watch, smart clothing,and/or smart glasses. In addition, the system controller 110 may beconfigured to communicate via the network with one or more other controlsystems (e.g., a building management system, a security system, etc.).

The mobile device 180 may be configured to transmit digital messages viaRF signals 109 to the system controller 110, for example, in one or moreInternet Protocol packets. For example, the mobile device 180 may beconfigured to transmit digital messages to the system controller 110over the LAN and/or via the Internet. The mobile device 180 may beconfigured to transmit digital messages over the internet to an externalservice, and then the digital messages may be received by the systemcontroller 110. The load control system 100 may comprise other types ofnetwork devices coupled to the network, such as a desktop personalcomputer (PC), a wireless-communication-capable television, or any othersuitable Internet-Protocol-enabled device.

The operation of the load control system 100 may be programmed andconfigured using, for example, the mobile device 180 or other networkdevice (e.g., when the mobile device is a personal computing device).The mobile device 180 may execute a graphical user interface (GUI)configuration software for allowing a user to program how the loadcontrol system 100 will operate. For example, the configuration softwaremay run as a PC application or a web interface. The configurationsoftware and/or the system controller 110 (e.g., via instructions fromthe configuration software) may generate a load control database thatdefines the operation of the load control system 100. For example, theload control database may include information regarding the operationalsettings of different load control devices of the load control system(e.g., the dimmer switch 120, the LED driver 130, the plug-in loadcontrol device 140, the motorized window treatments 150, and/or thethermostat 160). The load control database may comprise informationregarding associations between the load control devices and the inputdevices (e.g., the remote control device 170, the occupancy sensor 172,and/or the daylight sensor 174). The load control database may compriseinformation regarding how the load control devices respond to inputsreceived from the input devices. Examples of configuration proceduresfor load control systems are described in greater detail incommonly-assigned U.S. Pat. No. 7,391,297, issued Jun. 24, 2008,entitled HANDHELD PROGRAMMER FOR A LIGHTING CONTROL SYSTEM, and U.S.Pat. No. 10,027,127, issued Jul. 17, 2018, entitled COMMISSIONING LOADCONTROL SYSTEMS, the entire disclosures of which are hereby incorporatedby reference.

The system controller 110 may be configured to determine the location ofthe mobile device 180 and/or the occupant 182. The system controller 110may be configured to control (e.g., automatically control) the loadcontrol devices (e.g., the dimmer switch 120, the LED driver 130, theplug-in load control device 140, the motorized window treatments 150,and/or the temperature control device 160) in response to determiningthe location of the mobile device 180 and/or the occupant 182. Thesystem controller 110 may be configured to control the load controldevices according to occupant control parameters associated with theoccupant 182. The occupant control parameters may be predetermined orpreset settings for the occupant 182, biometric data for the occupant,and/or user input data received from the user via the mobile device 180.

One or more of the control devices of the load control system 100 maytransmit beacon signals, for example, RF beacon signals transmittedusing a short-range and/or low-power RF technology. The load controlsystem 100 may comprise at least one beacon transmitting device 184 fortransmitting the beacon signals. The beacon transmitting devices 184 maybe battery-powered (e.g., including a battery for powering the beacontransmitting device). The beacon transmitting device 184 may also beplugged into a receptacle to receive AC power and/or may be connected toan external power supply for receiving DC power. Any fixed-locationcontrol device of the load control system 100 (e.g., any of the loadcontrol devices, such as the dimmer switch 120, the LED driver 130, themotorized window treatments 150, and/or the temperature control device160) may be also be configured to transmit the beacon signals (e.g., tooperate beacon transmitting devices).

The mobile device 180 may be configured to receive a beacon signal whenlocated near a control device that is presently transmitting the beaconsignal. A beacon signal may comprise a unique identifier identifying thelocation of the load control device that transmitted the beacon signal.Since the beacon signal may be transmitted using a short-range and/orlow-power technology, the unique identifier may indicate the approximatelocation of the mobile device 180. The mobile device 180 may beconfigured to transmit the unique identifier to the system controller110, which may be configured to determine the location of the mobiledevice 180 using the unique identifier (e.g., using data stored inmemory or retrieved via the Internet). The system controller 110 may beconfigured to transmit control data (e.g., the determined locationand/or names of an area, groups, zones, electrical loads, controldevices, load control devices, input devices, presets, and/or scenesassociated with the location) back to the mobile device 180 and/orcontrol (e.g., automatically control) the load control devices inresponse to the location of the mobile device.

The system controller 110 may be configured to determine the location ofthe mobile device 180 using triangulation. Since the load controldevices of the load control system 100 may be mounted in fixedlocations, the load control devices may measure the signal strength ofRF signals received from the mobile device 180. The load control devicesmay transmit these signals strengths to the system controller 110, whichmay be configured to determine the location of the mobile device usingthe signal strengths. One or more load control devices of the loadcontrol system 100 may be movable devices. As such, the load controlsystem 100 may comprise fixed and movable load control devices. Anexample of a load control system for controlling one or more electricalloads in response to the position of a mobile device and/or occupantinside of a building is described in greater detail in commonly-assignedU.S. Patent Application Publication No. 2016/0056629, published Feb. 25,2016, entitled LOAD CONTROL SYSTEM RESPONSIVE TO LOCATION OF AN OCCUPANTAND MOBILE DEVICES, the entire disclosure of which is herebyincorporated by reference.

FIG. 2 is a block diagram of an example control device 200, which may bedeployed in a load control system (e.g., the load control system 100shown in FIG. 1). The control device 200 may comprise a control circuit210, which may include a first digital control circuit, such a primarymicroprocessor 212. The first digital control circuit may also comprise,for example, a microcontroller, a programmable logic device (PLD), anapplication specific integrated circuit (ASIC), a field-programmablegate array (FPGA), or any suitable processing device or control circuit.The control device 200 may comprise a memory (not shown) configured tostore operational characteristics of the control device. The memory maybe implemented as an external integrated circuit (IC) or as an internalcircuit of the control circuit 210.

The control device 200 may comprise a load control circuit 220 forcontrolling an electrical load, e.g., an external and/or internalelectrical load (not shown). The primary microprocessor 212 may beconfigured to generate one or more drive signals V_(DR) for controllingthe load control circuit 220 to control the electrical load (e.g., toturn the electrical load on or off, and/or to control the amount ofpower delivered to the electrical load). The primary microprocessor 212may also be configured to receive one or more feedback signals V_(FB)(e.g., indicating the magnitude of a load current conducted through theelectrical load and/or a load voltage developed across the electricalload) from the load control circuit 220. For example, the control device200 may comprise a dimmer switch (e.g., such as the dimmer switch 120shown in FIG. 1) and the load control circuit may comprise acontrollably conductive device, such as a thyristor (e.g., a triac) orone or more field-effect transistors (FETs), coupled in series with alighting load for controlling the amount of power delivered to thelighting load and thus an intensity of the lighting load. In addition,the control device 200 may comprise a light-emitting diode (LED) driver,and the load control circuit 220 may comprise an LED driver circuit forcontrolling the intensity (e.g., brightness) and/or color of one or moreLED light sources. The control device 200 may also comprise a motordrive unit for a motorized window treatment, and the load controlcircuit 220 may comprise a motor drive circuit (e.g., an H-bridge drivecircuit) for controlling a motor to adjust a position of a coveringmaterial of the motorized window treatment. For example, the feedbacksignals V_(FB) of the motorized window treatment may be generated by aHall-effect sensor circuit and may indicate a position of the coveringmaterial and/or direction of rotation of the motor.

The control device 200 may comprise a user interface 222, which maycomprise, for example, one or more actuators (e.g., buttons) forreceiving user inputs and/or one or more visual indicators for providinguser feedback. For example, if the control device 200 comprises awall-mounted dimmer switch (e.g., such as the dimmer switch 120 shown inFIG. 1), the user interface 220 may comprise a toggle actuator and anintensity adjustment actuator (e.g., such as a slider control or a pairof raise and lower buttons) for controlling a lighting load. Inaddition, if the control device 200 comprises a remote control device(e.g., such as the remote control device 170 shown in FIG. 1), the userinterface 222 may comprise one or more buttons for controlling one ormore electrical loads, for example, by selecting preset (e.g., scenes)of the load control system. The user interface 222 may also comprise oneor more light-emitting diodes (LEDs) for illuminating the visualindicators, for example, to provide a visual indication of a statusand/or a present intensity of a lighting load, and/or a visualindication of a selected preset. The primary microprocessor 212 of thecontrol circuit 210 may be configured to control the load controlcircuit 220 in response to actuations of the actuators of the userinterface 222, and may be coupled to the LEDs for illuminating thevisual indicators to provide feedback.

The control device 200 may also comprise a sensing circuit 224configured to detect and/or measure one or more environmentalcharacteristics in the environment of the control device. For example,the sensing circuit 224 may comprise an occupancy detection circuitconfigured to detect an occupancy or vacancy condition in the vicinityof the control device 200. The sensing circuit 224 may include adetector, such as, for example, a pyroelectric infrared (PIR) detector,an ultrasonic detector, and/or a microwave detector, for detecting anoccupancy or vacancy condition in the vicinity of the control device200. The control circuit 210 may be configured to determine a vacancycondition in the space after a timeout period expires since the lastoccupancy condition was detected. The control circuit 210 may beconfigured to control the load control circuit 220 to control theintensity of the electrical load in response to the sensing circuit 224detecting occupancy and/or vacancy conditions. The sensing circuit 224may also comprise a daylight sensing circuit (e.g., including aphotodiode) for measuring an ambient light level in the space around thecontrol device 200. In addition, the sensing circuit 224 may comprise atemperature sensing circuit for measuring a present temperature in thevicinity of the control device 200.

The control device 200 may comprise a power source 230 (e.g., aninternal power source) for producing a direct-current (DC) voltageV_(PS). For example, the power source 230 may comprise one or morebatteries and/or a photo-voltaic power source (e.g., a solar cell). Inaddition, the power source 230 may comprise one or more energy storageelements, such as super capacitors and/or rechargeable batteries,configured to charge from an external DC power supply via a power bus.The control device 200 may also comprise a power supply 232 that mayreceive the DC voltage V_(PS) and generate a low-voltage DC supplyvoltage V_(CC) across a capacitor C234 (e.g., an energy storagecapacitor) for powering the control circuit 210, the user interface 222,the sensing circuit 224, and other low-voltage circuitry of the controldevice 200. For example, if the control device 200 comprises a motordrive unit for a battery-powered motorized window treatment, the loadcontrol circuit 220 may receive power from the power source 230 (e.g.,directly from the DC voltage V_(PS)), while the other circuitry may bepowered from the DC supply voltage V_(CC). In addition, the low-voltagecircuitry of the control device 200 may also be powered (e.g., directlypowered) from the DC voltage V_(PS) produced by the power source (e.g.,the control device 200 may not comprise the power supply 232). Further,the control device 200 may also receive power from an external powersource, such as an alternating-current (AC) power source (not shown).For example, if the control device 200 comprises a dimmer switch (e.g.,a two-wire dimmer switch), the power supply 232 may be electricallycoupled in parallel with the controllably conductive device of the loadcontrol circuit 220 for conducting a charging current to generate the DCsupply voltage V_(CC) when the controllably conductive device isnon-conductive. The power supply 232 may also be configured to conductthe charging current through an earth ground connection.

The control device 200 may comprise a wireless communication circuit 240configured to communicate (e.g., transmit and/or receive) wirelesssignals, such as RF signals (e.g., the RF signals 108 shown in FIG. 1).The wireless communication circuit 240 may comprise an antenna 242 fortransmitting and receiving the RF signals and a surface acoustic wave(SAW) filter 244 (e.g., which may be optional). The wirelesscommunication circuit 240 may comprise two radio circuits: a primaryradio circuit 246 (e.g., a first radio circuit) and a secondary radiocircuit 248 (e.g., a second radio circuit). The primary and secondaryradio circuits 246, 248 may be coupled (e.g., selectively and/orcontrollably coupled) to the SAW filter 244 via an RF switch 245. Theprimary microprocessor 212 may generate a switch control signal V_(SW)for controlling the RF switch 245 to be connected to a first contact 245a or a second contact 245 b. The primary microprocessor 212 may beconfigured to control the RF switch 245 to allow the secondary radiocircuit 248 to monitor for transmitted RF signals most of the time(e.g., when RF signals are not being transmitted by other controldevices) and then change to allow the primary radio circuit 246 toreceive one of the RF signals (e.g., in response to the secondary radiocircuit 248 detecting an RF signal), such that the primary radio circuit246 is enabled (e.g., only enabled) for short periods of time (e.g., anRF signal is being transmitted by another control device).

The primary radio circuit 246 may comprise an RF transceiver fortransmitting and receiving the RF signals via the antenna 242 when theRF switch 245 is connected to the first contact 245 a. In addition, theprimary radio circuit 246 may simply comprise an RF receiver. Theprimary radio circuit 246 may be coupled to the primary microprocessor212 for communicating message signals V_(MSG) (e.g., the digitalmessages transmitted and received via the antenna 242) with the primarymicroprocessor. The primary radio circuit 246 may be powered from the DCsupply voltage V_(CC). The primary radio circuit 246 may be configuredto communicate RF signals on one or more communication channels (e.g.,frequencies), which may be adjusted by the primary microprocessor 212.The primary radio circuit 246 may receive a first enable control signalV_(EN1) from the primary microprocessor 212 for enabling and disablingthe primary radio circuit 246 (e.g., controlling the primary radiocircuit in and out of a sleep mode). The primary microprocessor 212 mayalso be configured to enter a sleep mode when the primary radio circuit246 is in the sleep mode. The primary microprocessor 212 and the primaryradio circuit 246 may both be configured to consume less power in thesleep more than when awake in a normal operation mode. The primarymicroprocessor 212 may be configured to control the load control circuit220 to control the electrical load in response to digital messagesreceived from the primary radio circuit 246 via the message signalsV_(MSG). The primary microprocessor 212 may be configured to control thevisual indicators of the user interface 222 in response to digitalmessages received from the primary radio circuit 246 via the messagesignals V_(MSG). The primary microprocessor 212 may be configured totransmit digital messages for controlling an electrical load via theprimary radio circuit 246 in response to the user interface 222 and/orthe sensing circuit 224.

The secondary radio circuit 246 may comprise an RF receiver forreceiving the RF signals via the antenna 242 when the RF switch 245 isconnected to the second contact 245 b (e.g., as shown in FIG. 2). Forexample, the secondary radio circuit 246 may comprise part numberMAX7033, manufactured by Maxim Integrated. The secondary radio circuit248 may be powered from the DC supply voltage V_(CC). The secondaryradio circuit 248 may be characterized by a smaller power dissipation(e.g., power consumption) than the primary radio circuit 246. Forexample, the primary radio circuit 246 may be characterized by a typicalpower dissipation of approximately 48 mW, while the secondary radiocircuit 248 may be characterized by a typical power dissipation ofapproximately 19 mW. The secondary radio circuit 248 may be configuredto receive RF signals on a single communication channel (e.g.,frequency). The secondary radio circuit 248 may be configured togenerate a received signal strength identifier (RSSI) signal V_(RSSI),which may have a magnitude that may indicate the signal strength of theRF signals received via the antenna 242 when the RF switch 245 isconnected to the second contact 245 b. The received signal strengthidentifier signal V_(RSSI) generated by the secondary radio circuit 248may be characterized by a fast stabilization time (e.g., approximately200-250 microseconds). In addition, the secondary radio circuit 248 maysimply comprise a received signal strength measurement circuit. Further,the secondary radio circuit 248 may comprise an RF transceiverconfigured to generate the received signal strength identifier signalV_(RSSI).

The primary microprocessor 212 may be configured to control the primaryradio circuit 246 in and out of the sleep mode in response to thesecondary radio circuit 214. The control circuit 210 may comprise asecond digital control circuit, such as a secondary microprocessor 214,for interfacing between the primary microprocessor 212 and the secondaryradio circuit 248. The second digital control circuit may also comprise,for example, a microcontroller, a programmable logic device (PLD), anapplication specific integrated circuit (ASIC), a field-programmablegate array (FPGA), or any suitable processing device or control circuit.The secondary microprocessor 214 may generate a wake-up control signalV_(WAKE_UP) for waking up the primary microprocessor 212 from the sleepmode. For example, the wake-up control signal V_(WAKE_UP) may bereceived at an interrupt pin of the primary microprocessor 212. Thesecondary microprocessor 214 may receive the received signal strengthidentifier signal V_(RSSI) generated by the secondary radio circuit 248at an analog-to-digital converter (ADC) port of the secondarymicroprocessor. The secondary microprocessor 214 may generate a secondenable control signal V_(EN2) for enabling and disabling the secondaryradio circuit 248 (e.g., controlling the secondary radio circuit in andout of a sleep mode during which the secondary radio circuit may consumeless power). The secondary microprocessor 214 may also generate a thirdenable control signal V_(EN3) for enabling and disabling the powersupply 232. When the secondary radio circuit 248 is in the sleep mode(e.g., disabled), the secondary microprocessor 214 may also beconfigured to enter a sleep mode during which the secondarymicroprocessor may consume less power. The secondary microprocessor 214may be configured to exit the sleep mode before (e.g., immediatelybefore) enabling the secondary radio circuit 248 and enter the sleepmode after (e.g., immediate after) disabling the secondary radiocircuit. The secondary microprocessor 214 may be configured to exit thesleep mode in response to an internal timer of the secondarymicroprocessor.

The secondary microprocessor 214 may be configured to enable (e.g.,periodically enable) the secondary radio circuit 248 (e.g.,approximately every 17.6 milliseconds), wait for a wait time periodT_(WAIT) (e.g., approximately 250 microseconds) until the magnitude ofthe received signal strength identifier signal V_(RSSI) has stabilized(e.g., reached a steady state value), and then sample the receivedsignal strength identifier signal V_(RSSI). If the magnitude of thereceived signal strength identifier signal V_(RSSI) exceeds a thresholdV_(TH) (e.g., indicating that the magnitude of the received RF signalexceeds approximately −90 dBm), the secondary microprocessor 214 maydetermine that an RF signal is presently being transmitted by anothercontrol device and may control the wake-up control signal V_(WAKE-UP) towake up the primary microprocessor 212 from the sleep mode into a normaloperation mode. After waking up, the primary microprocessor 212 maycontrol the switch control signal V_(SW) to adjust the RF switch 245from the second contact 245 b to the first contact 245 a, and controlthe first enable control signal V_(EN1) to wake up the primary radiocircuit 246, such that the primary radio circuit 246 may receive RFsignals via the antenna 242. The primary microprocessor 212 may beconfigured to enter the sleep mode after any required processing iscomplete, e.g., after transmitting and/or receiving of digital messageis complete and/or after any processing required in response to areceived digital message is complete. The secondary microprocessor 214may also be configured to enter the sleep mode after the primarymicroprocessor 212 has entered the sleep mode.

FIG. 3 is a timing diagram illustrating example waveforms of a controldevice (e.g., one of the control devices of the load control system 100of FIG. 1 and/or the control device 200 of FIG. 2) during a datatransmission event. For example, the data transmission event may involvethe transmission of a particular digital message (e.g., including acommand) transmitted by a transmitting device (e.g., the remote controldevice 170) to the control device 200. During the data transmissionevent, the transmitting device may transmit packets 300 (e.g., with eachpacket including the same digital message and/or command) via RF signals(e.g., RF signals 108). Each packet 300 transmitted by the transmittingdevice may have a length equal to a packet time period T_(PACKET) (e.g.,approximately 5 milliseconds). Each packet 300 may be transmittedmultiple times (e.g., up to twelve times) during the data transmissionevent. For example, four packets 300 are shown in FIG. 3 even though thedata transmission event may include more packets. Between each packet300, there may be a packet break time period T_(PKT-BRK) (e.g.,approximately 75 milliseconds), such that the transmitting devicetransmits packets of data at a transmission rate of approximately 12.5packets per second. Alternatively, the break time period T_(PKT-BRK) maynot be a fixed value, but may be a varying or random time between eachof the transmitted packets 300.

While the control device 200 is not receiving RF signals (e.g., thepackets 300) via the wireless communication circuit 240, the primarymicroprocessor 212 and the primary radio circuit 246 may each be in thesleep mode. At this time, the first enable control signal V_(EN1) may below (e.g., at circuit common), which may cause the first radio circuit246 to be in the sleep mode. In addition, the switch control signalV_(SW) may be low (e.g., at circuit common), which may cause the RFswitch 245 to be connected to the second contact 245 b. In addition, thethird enable control signal V_(EN3) may be low (e.g., at circuitcommon), which may disable the power supply 232. While the power supply232 is disabled, the primary microprocessor 212 and the secondarymicroprocessor 214 may draw a small amount of current from the capacitorC234.

The secondary microprocessor 214 may periodically drive the secondenable control signal V_(EN2) high towards the DC supply voltage V_(CC)to periodically wake up the secondary radio circuit 248 to see if anycontrol devices are presently transmitting one of the packets 300. Forexample, the secondary microprocessor 214 may enable the secondary radiocircuit 248 for a sampling time period T_(SMPL-RF) (e.g., approximately300 microseconds) before driving the second enable control signalV_(EN2) low towards circuit common. The secondary microprocessor 214 maydrive the second enable control signal V_(EN2) high to start thesampling time period T_(SMPL-RF) periodically according to a wake-upperiod T_(WAKE-UP) (e.g., every 17.6 milliseconds). The secondary radiocircuit 248 may consume (e.g., only consume) significant power duringthe sampling time periods T_(SMPL-RF).

Prior to enabling the secondary radio circuit 248 during each samplingtime period T_(SMPL-RF), the secondary microprocessor 214 may drive thethird enable control signal V_(EN3) high to enable the power supply 232.For example, the secondary microprocessor 214 may drive the third enablecontrol signal V_(EN3) high to enable the power supply 232 at thebeginning of a power-supply stabilization time period T_(PS-STB) beforedriving the second enable control signal V_(EN2) high to enable thesecondary radio circuit 248. The power-supply stabilization time periodT_(PS-STB) may allow the magnitude of the supply voltage V_(CC) tostabilize (e.g., reach a steady-state value) before the secondary radiocircuit 248 is enabled. The secondary microprocessor 214 may keep thepower supply 232 enabled until the end of the sampling time periodT_(SMPL-RF), such that the power supply is periodically enabled for apower-supply enable time period T_(PS-EN).

During each sampling time period T_(SMPL-RF), the secondarymicroprocessor 214 may wait for the wait time period T_(WAIT) to allowthe magnitude of the received signal strength identifier signal V_(RSSI)to stabilize before trying to determine if a packet 300 is beingtransmitted during that sampling time period. At the end of the waittime period T_(WAIT), the secondary microprocessor 214 may sample thereceived signal strength identifier signal V_(RSSI) and compare thesampled magnitude to the threshold V_(TH) to determine if a packet 300is being transmitted during the sampling time period T_(SMPL-RF). If thesecondary microprocessor 214 determines that a packet 300 is not beingtransmitted during the RF sample time period T_(SMPL-RF), the secondaryprocessor 214 may drive the second enable control signal V_(EN2) low tocause the secondary radio circuit 248 to enter the sleep mode for an RFsleep time period T_(SLP-RF). In addition, the secondary processor 214may drive the third enable control signal V_(EN3) low to disable thepower supply 232 if the secondary microprocessor 214 determines that apacket 300 is not being transmitted during the RF sample time periodT_(SMPL-RF).

If a packet 300 is being transmitted during the RF sample time periodT_(SMPL-RF), the magnitude of the received signal strength identifiersignal V_(RSSI) may increase from a minimum magnitude (e.g., zero) to asteady-state magnitude V_(SS) (e.g., as shown between times t₀ and t₁ inFIG. 3). The secondary microprocessor 214 may wait for the wait timeperiod T_(WAIT) after driving the second enable control signal V_(EN2)high (e.g., at time t₀) to allow the magnitude of the received signalstrength identifier signal V_(RSSI) to stabilize at the steady-statemagnitude V_(SS). The secondary microprocessor 214 may then sample thereceived signal strength identifier signal V_(RSSI) at the end of thewait time period T_(WAIT) (e.g., at time t₁ or slightly before time t₁).If the magnitude of the received signal strength identifier signalV_(RSSI) (e.g., the steady-state magnitude V_(SS)) is greater than orequal to the threshold V_(TH), the secondary microprocessor 214 maydrive the wake-up control signal V_(WAKE-UP) high towards the DC supplyvoltage V_(CC) for a pulse time period T_(PULSE), before subsequentlydriving the wake-up control signal V_(WAKE-UP) low. The primarymicroprocessor 212 does not go back to the sleep mode in response thewake-up control signal V_(WAKE-UP) being drive low, but will enter thesleep mode after all necessary processing is complete. The secondarymicroprocessor 214 may also maintain the third enable control signalV_(EN3) high to keep the power supply 232 enabled after pulsing thewake-up control signal V_(WAKE-UP).

In response to detecting that the wake-up control signal V_(WAKE-UP) hasbeen driven high, the primary microprocessor 212 may wake up, drive theswitch control signal V_(SW) high to change the RF switch 245 to thefirst contact 245 a (e.g., as shown at time t₂ in FIG. 3), and drive thefirst enable control signal V_(EN1) high to wake-up the primary radiocircuit 246 (e.g., as shown at time t₃ in FIG. 3). Since the primaryradio circuit 246 is awake when the next packet 300 is transmitted(e.g., between times t₄ and is in FIG. 3), the primary radio circuit 246may be configured to receive the packet 300 and the primarymicroprocessor 212 may be configured to process and respond to thepacket. After the primary microprocessor 212 has processed the packetand determined that there are no more packets to transmit or receiveand/or all necessary processing in response to the received digitalmessage is complete, the primary microprocessor 212 may drive the firstenable control signal V_(EN1) low (e.g., as shown at time t₆ in FIG. 3).The primary microprocessor 212 may then drive the switch control signalV_(SW) low to change the RF switch 245 back to the second contact 245 b(e.g., as shown at time t₇ in FIG. 3) before entering the sleep mode. Inresponse to detecting that the switch control signal V_(SW) was drivenlow, the secondary microprocessor 214 may subsequently drive the thirdenable control signal V_(EN3) low to disable the power supply 232 (e.g.,as shown at time t₈ in FIG. 3). The secondary microprocessor 214 maythen begin to periodically drive the second enable control signalV_(EN2) high during the RF sample time period T_(SMPL-RF) once again todetermine if any control devices are presently transmitting another oneof the packets 300.

The RF sample time period T_(SMPL-RF) and the RF sleep time periodT_(SLP-RF) may be sized appropriately to ensure that the RF sample timeperiod T_(SMPL-RF) coincides with at least one packet 300 of apredetermined number of consecutive packets of a data transmission event(e.g., as described in greater detail in previously-referenced U.S. Pat.No. 10,041,292). As a result, the RF sleep time period T_(SLP-RF) may bemuch longer than the packet time period T_(PACKET). In addition, the RFsample time period T_(SMPL-RF) may be significantly shorter than thepacket time period T_(PACKET). For example, as shown in FIG. 3, thefirst two packets 300 do not coincide with the RF sample time periodT_(SMPL-RF) when the secondary radio circuit 248 is awake. At least aportion of the third packet 300 falls with the next RF sample timeperiod T_(SMPL-RF), such that the secondary microprocessor 214 may beable to detect the packet and wake up the primary microprocessor 212.The primary microprocessor 212 may then wake up the primary radiocircuit 246, which is able to receive the fourth packet 300. Since thesecondary radio circuit 248 periodically wakes up to determine if apacket is being transmitted (e.g., rather than the primary radio circuit246 waking up) and the secondary radio circuit consumes less power thanthe primary radio circuit, the control device may have a significantpower savings as compared to prior art control devices having RFreceivers and/or transceivers.

While FIGS. 2 and 3 show the primary microprocessor 212 generating theswitch control signal V_(SW) for controlling the RF switch 245, thesecondary microprocessor 214 could also generate the switch controlsignal V_(SW). For example, after detecting that a packet 300 ispresently being transmitted, the secondary microprocessor 214 may drivethe wake-up control signal V_(WAKE-UP) high to wake up the primarymicroprocessor 212 and drive the switch control signal V_(SW) high tochange the RF switch 245 to the first contact 245 a. The secondarymicroprocessor 214 may cease periodically enabling the secondary radiocircuit 248 and maintain the switch control signal V_(SW) high while theprimary radio circuit 246 is awake. The secondary microprocessor 214 maydrive the switch control signal V_(SW) low to change the RF switch 245to the second contact 245 b and begin periodically enabling thesecondary radio circuit 248 again in response to receiving from theprimary microprocessor 212 an indication that the primary radio circuit246 is in the sleep mode (e.g., in response to the switch control signalV_(SW) being driven low). In addition, the RF switch 245 may becontrolled between the first contact 245 a and the second contact 245 bin response to the wake-up control signal V_(WAKE-UP) and the secondarymicroprocessor 214 may be configured to maintain the wake-up controlsignal V_(WAKE-UP) high while the primary radio circuit 246 is awake(e.g., the switch control signal V_(SW) may not be generated by eitherthe primary microprocessor 212 or the secondary microprocessor 214).

FIG. 4 is a flowchart of an example control procedure 400 that may beexecuted by a control circuit of a control device (e.g., the secondarymicroprocessor 214 of the control device 200) to periodically wake up aradio circuit (e.g., the secondary radio circuit 248) to determine if anRF signal (e.g., a packet) is presently being transmitted. The controlcircuit may generate a wake-up signal V_(WAKE-UP) for causing anothercontrol circuit (e.g., the primary microprocessor 212) to wake upanother radio circuit (e.g., the primary radio circuit 246). Forexample, the control procedure 400 may be executed when the controldevice wakes up from a sleep mode at 410 (e.g., in response to aninternal timer of the control device). At 412, the control circuit mayfirst drive the second enable control signal V_(EN2) high to enable thesecondary radio circuit 248. At 414, the control circuit may wait for await time period T_(WAIT) to allow the magnitude of the received signalstrength identifier signal V_(RSSI) generated by the secondary radiocircuit 248 to stabilize. The control circuit may sample the receivedsignal strength identifier signal V_(RSSI) at 416 (e.g., at the end ofthe wait time period T_(WAIT)). If the magnitude of the received signalstrength identifier signal V_(RSSI) is not greater than or equal to athreshold V_(TH) (e.g., indicating that the magnitude of the received RFsignal does exceeds approximately −90 dBm) at 418, the control circuitmay drive the second enable control signal V_(EN2) low at 420 and enterthe sleep mode at 422, before the control procedure 400 exits.

If the magnitude of the received signal strength identifier signalV_(RSSI) is greater than or equal to the threshold V_(TH) (e.g.,indicating that the magnitude of the received RF signal exceedsapproximately −90 dBm) at 418, the control circuit may drive the wake-upsignal V_(WAKE-UP) high for a pulse time period T_(PULSE) at 424. Inresponse to detecting the pulse in the wake-up signal V_(WAKE-UP), theother control circuit (e.g., the primary microprocessor 212) may wake upthe other radio circuit (e.g., the primary radio circuit 246). At 426,the control circuit may wait until the other control circuit indicatesthat the other radio circuit has been put back to sleep (e.g., bydetermining when the primary microprocessor 212 has driven the switchcontrol signal V_(SW) low). When the switch control signal V_(SW) hasbeen driven low at 426, the control circuit may then drive the secondenable control signal V_(EN2) low at 420 and enter the sleep mode at422, before the control procedure 400 exits.

FIG. 5 is a flowchart of an example control procedure 500 that may beexecuted by a control circuit of a control device (e.g., the primarymicroprocessor 212 of the control device 200) to wake up a radio circuit(e.g., the primary radio circuit 246) and receive a digital message(e.g., a packet) via RF signals. The control circuit may execute thecontrol produce 500 in response to receiving a wake-up signal (e.g., thewake-up signal V_(WAKE-UP) from the secondary microprocessor 214) at510. At 512, the control circuit may first drive the switch controlsignal V_(SW) high to adjust the RF switch 245 from the second contact245 b to the first contact 245 a (e.g., to connect the primary radiocircuit 246 to the antenna 242). At 514, the control circuit may drivethe first enable control signal V_(EN1) high to enable the radiocircuit. If the control circuit receives a message via the primary radiocircuit 246 at 516 before a timeout expires at 518, the control circuitmay process the received message at 520. For example, the controlcircuit may control a load control circuit (e.g., the load controlcircuit 220) to control an electrical load, illuminate visual indicators(e.g., visual indicators of the user interface 222) to provide feedback,and/or transmit a message via the primary radio circuit 246 in responseto the received message at 520. The control circuit may then drive thefirst enable control signal V_(EN1) low to cause the primary radiocircuit 246 to enter the sleep mode at 522. If the timeout expires at518 before the control circuit receive a message at 516, the controlcircuit may simply put the primary radio circuit 246 in the sleep modeat 522. At 524, the control circuit may drive the switch control signalV_(SW) low at 524 to adjust the RF switch 245 from the first contact 245a to the second contact 245 b. At 526, the control circuit may enter thesleep mode, before the control procedure 500 exits.

While the control device 200 has been described herein with the controlcircuit 210 comprising the primary microprocessor 212 and the secondarymicroprocessor 214, the functions of the control circuit 210 could beimplemented by a single microprocessor and/or additionalmicroprocessors. In addition, the either or both of the primarymicroprocessor 212 and the secondary microprocessor 214 may beimplemented on a single integrated circuit including either or both ofthe primary radio circuit 246 and the secondary radio circuit 248. Forexample, the primary microprocessor 212 and the primary radio circuit246 may be implemented on a single integrated circuit, and/or thesecondary microprocessor 214 and the secondary radio circuit 248 may beimplemented on a single integrated circuit. Further, the primary radiocircuit 246 and the secondary radio circuit 248 may be implemented in asingle integrated circuit.

Although features and elements may be described herein in particularcombinations, each feature or element may be used alone or in anycombination with the other features and elements. While this disclosurehas been described in terms of certain embodiments and generallyassociated methods, alterations and permutations of the embodiments andmethods will be apparent to those skilled in the art. Accordingly, theabove description of example embodiments does not constrain thisdisclosure. Other changes, substitutions, and alterations are alsopossible without departing from the spirit and scope of this disclosure.

What is claimed is:
 1. A control device comprising: a primary radiocircuit configured to receive radio-frequency signals via an antenna; acontrol circuit coupled to the primary radio circuit, the controlcircuit configured to control the primary radio circuit into a sleepmode; and a secondary radio circuit configured to generate a firstcontrol signal indicating that a radio-frequency signal is presentlybeing transmitted by an external device; wherein the control circuit isconfigured to wake up the primary radio circuit from the sleep mode inresponse to the secondary radio circuit generating the first controlsignal indicating that the radio-frequency signal is presently beingtransmitted by the external device.
 2. The control device of claim 1,wherein the control circuit comprises a primary microprocessorconfigured to process the radio-frequency signals received via theprimary radio circuit and control the primary radio circuit into and outof the sleep mode.
 3. The control device of claim 2, wherein the controlcircuit comprises a secondary microprocessor configured to receive thefirst control signal from the secondary radio circuit, and generate asecond control signal in response to determining that theradio-frequency signal is presently being transmitted by the externaldevice.
 4. The control device of claim 3, wherein the secondarymicroprocessor is configured to periodically wake up the secondary radiocircuit to determine if a radio-frequency signal is being transmitted bythe external device.
 5. The control device of claim 4, wherein thecontrol signal generated by the secondary radio circuit has a magnitudethat indicates a signal strength of a received RF signal, the secondarymicroprocessor configured to wait for a wait time period after waking upthe secondary radio circuit before sampling the control signal generatedby the secondary radio circuit.
 6. The control device of claim 5,wherein, when a magnitude of the control signal generated by thesecondary radio circuit exceeds a threshold, the secondarymicroprocessor is configured to generate the second control signal toindicate that the radio-frequency signal is presently being transmittedby the external device.
 7. The control device of claim 3, wherein theprimary microprocessor is configured to enter a sleep mode, and wake upfrom the sleep mode in response to receiving the second control signalfrom the secondary microprocessor.
 8. The control device of claim 7,wherein the primary microprocessor is configured to wake up the primaryradio circuit from the sleep mode in response to receiving the secondcontrol signal from the secondary microprocessor.
 9. The control deviceof claim 3, wherein the secondary microprocessor and the secondary radiocircuit are implemented on a single integrated circuit.
 10. The controldevice of claim 3, wherein the primary radio circuit and the secondaryradio circuit are implemented on a single integrated circuit.
 11. Thecontrol device of claim 1, further comprising: a load control circuitfor controlling an electrical load; wherein the control circuit isconfigured to receive a message via the primary radio circuit afterwaking up the primary radio circuit and control the load control circuitto control the electrical load in response to the message.
 12. Thecontrol device of claim 11, wherein the electrical load comprises alighting load, and the load control circuit comprises a controllablyconductive device coupled in series with the lighting load forcontrolling an amount of power delivered to the lighting load.
 13. Thecontrol device of claim 11, wherein the electrical load comprises amotor, and the load control circuit comprises a motor drive circuit forcontrolling the motor to adjust a position of a covering material of amotorized window treatment.
 14. The control device of claim 1, furthercomprising: a radio-frequency switch configured to selectively couplethe antenna to the primary radio circuit and the secondary radiocircuit.
 15. The control device of claim 11, wherein the primarymicroprocessor is configured to control the radio-frequency switch toconnect the primary radio circuit to the antenna in response to thesecondary radio circuit generating the first control signal indicatingthat the radio-frequency signal is presently being transmitted by theexternal device.
 16. The control device of claim 1, wherein thesecondary radio circuit consumes less power than the primary radiocircuit.
 17. The control device of claim 16, further comprising: abattery for powering the primary and secondary radio circuits and thecontrol circuit.
 18. The control device of claim 1, further comprising:a user interface comprising one or more actuators for receiving userinputs; wherein the control circuit is configured to transmit a firstdigital message for controlling an electrical load via the primary radiocircuit in response an actuation of one of the actuators of the userinterface.
 19. The control device of claim 18, wherein the controlcircuit is configured to illuminate at least one visual indicator of theuser interface in response to a second digital message received via theprimary radio circuit.
 20. The control device of claim 1, furthercomprising: a sensing circuit configured to detect one or moreenvironmental characteristics in an environment of the control device;wherein the control circuit is configured to transmit a digital messagefor controlling an electrical load via the primary radio circuit inresponse the sensing circuit.
 21. The control device of claim 1, whereinthe secondary radio circuit is configured to wake up periodically todetermine if a radio-frequency signal is being transmitted by theexternal device.
 22. The control device of claim 1, wherein the controlsignal generated by the secondary radio circuit has a magnitude thatindicates a signal strength of a received RF signal.
 23. The controldevice of claim 1, wherein the primary microprocessor and the primaryradio circuit are implemented on a single integrated circuit.